12/15/2023 0 Comments Gummy stem blight of watermelon![]() ![]() ![]() Petiole and stem tissue affected on older plants is water-soaked, tan, and develops a characteristic reddish brown gummy exudate. When seedling stems are infected the tissue often appears water-soaked and can lead to girdling which kills the plant. They can rapidly enlarge becoming irregular. Leaf spots initially are round or triangular when beginning at the leaf margin. Gummy stem blight is the disease name used when symptoms develop on stems and leaves. Fruit rot is most common in pumpkin and winter squashes. Melons are more susceptible to stem cankers than other cucurbits while stems of butternut and related squashes ( Cucurbita moschata) are resistant. Butternut squash and summer squashes are least susceptible. Leaves including cotyledons of all melons are especially susceptible while those of cucumber and some squashes are initially resistant and become susceptible as they age. The pathogen’s previous name was Didymella bryoniae.Īll cucurbit crops are susceptible. Three species of Stagonosporopsis cause this disease. Its spores are moved by splashing water and wind. states, as well as in subtropical and tropical areas of the world. This disease is more common in humid southern U.S. Infection occurs when warm (64-82 C), with 75-77 being optimal. Frequent rain and overhead irrigation done when foliage won’t dry promptly (such as when irrigation ends after sunset) promote disease development. Most important is high humidity and plant tissue (in particular leaves) staying wet for at least an hour for infection, longer for lesion development. Gsb-7(t) gene mapping gummy stem blight melon resistance gene.This disease has been observed sporadically and uncommonly on Long Island, likely reflecting the pathogen, a fungus, not being established and surviving in the area rather than conditions not being favorable. Our results offer new genetic resources and will be helpful for the development of GSB-resistant melon cultivars in the future. bryoniae at 24 h postinoculation, indicating that the MELO3C010403-T2 transcript of MELO3C010403 was the most likely candidate gene of Gsb-7(t). Gene expression analysis showed that expression of MELO3C010403-T2 but not MELO3C010403-T1 was significantly induced by D. The MELO3C010403 gene contains two alternative transcripts, MELO3C010403-T1 and MELO3C010403-T2, with five and seven nonsynonymous mutation sites, respectively. Ten putative genes were annotated in this region that contains a wall-associated receptor kinase (WAK) gene MELO3C010403. The Gsb-7(t) gene was finally delimited to a 140-kb interval on chromosome 7 using bulked segregant analysis and chromosome walking strategies. To further understand the resistance mechanism of H55R against GSB, an F 2 population was obtained from a cross between the GSB-susceptible line A15 and H55R, and genetic analysis indicated that the GSB resistance in H55R was controlled by a single dominant gene, tentatively named Gsb-7(t). In this study, 260 melon germplasm resources were screened for resistance to GSB, and an inbred line, H55R, that exhibited immunity to GSB was identified. Breeding GSB-resistant cultivars with host resistance genes is considered the most economic and effective strategy to control this disease. Gummy stem blight (GSB), caused by Didymella bryoniae, is a devastating fungal disease of melon worldwide. ![]()
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